Ozone currently has many widespread industrial applications including: the destruction organic and inorganic contaminants in wastewater and sludge (U.S. Pat. No. 5,637,231); disinfection (U.S. Pat. No. 5,614,151); environmentally friendly bleaching of paper (U.S. Pat. No. 5,658,429); etching surfaces of semiconductors (U.S. Pat. No. 5,599,740); decolorizing water; removing odor from clothing (U.S. Pat. No. 5,611,868); and killing insects, etc. Like chlorine gas, fluorine gas, chlorine oxide compounds and hydrogen peroxide, ozone is a strong oxidizing agent. However, ozone is less environmentally hazardous than the aforementioned oxidizing agents, and has well-known environmental advantages over other strong oxidizing agents. For example, chlorine containing compounds leave behind an undesirable chlorine residue, and fluorine gas is highly corrosive and requires special handling.
Ozone, O.sub.3, is made from stable molecular oxygen, O.sub.2. However, ozone is unstable at ambient temperatures and decomposes rapidly. Because ozone decomposes at ambient temperature, it must be manufactured on-site for industrial applications. Current technology in ozone production is carried out by one of two general techniques. One general technique utilizes electrochemical techniques to generate ozone atoms. See, for example, U.S. Pat. Nos. 3,256,164; 4,135,995; 4,316,782; 4,375,395; 5,332,563; 5,407,550 and 5,460,705. Electrochemical techniques require electrochemical cells composed of an anode and a cathode conducting electricity through a solution or a solid. The electrochemical cells produce toxic by-products that can be difficult to dispose. The systems utilizing electrochemical techniques also suffer from high electrical consumption.
For example, U.S. Pat. No. 5,407,550 requires an electrochemical cell to produce ozone. The electrochemical cell uses an anode and a cathode to conduct electricity through a solution or a solid. The system described in U.S. Pat. No. 5,407,550 also requires a perfluorocarbon sulfonic acid-based ion-exchange membrane as the electrolyte.
The second general technique utilizes electrical discharge to generate ozone atoms. See, for example, U.S. Pat. Nos. 4,131,528; 3,309,300; 3,654,126; 5,366,703; 5,223,105; 3,921,002; 4,417,966; 5,098,671; 5,124,132; 5,370,846 and 4,863,701. The above-referenced systems utilizing electrical discharge also suffer from high electrical consumptions and a low conversion efficiencies from oxygen to ozone.
U.S. Pat. No. 4,863,701 describes a system which passes an electrical discharge through an oxygen gas and converts oxygen to ozone. U.S. Pat. No. 4,863,701 does not incorporate inert gases to boost efficiency and does not utilize a loop to recycle the oxygen not converted to ozone.
U.S. Pat. No. 5,370,846 uses argon and helium gases and a specific type of silent discharge to produce ozone. However, U.S. Pat. No. 5,370,846 only uses gas mixtures for argon and helium in the 1-10 percent range. There is no loop for the recycling of the inert gas-oxygen mixture. No catalytic advantage was demonstrated for the inert gases. The efficiency demonstrated for inert gas argon-helium-oxygen mixtures in the generator are less than for a nitrogen-oxygen mix.
There are other specific methods of producing ozone using high energy methods, for example UV light, beta rays or lasers, to convert oxygen to ozone, but these methods have not found significant commercial application. U.S. Pat. Nos. 3,702,973 and 5,387,400 are examples of such highly specific methods. Current applications of ozone are limited by the cost of instrumentation required for ozone production, the high consumption of electricity during ozone production and the low efficiencies of current methods of converting oxygen to ozone.